Make a fiberglass fan shroud
(Finalized transfer of generalized fiberglass text into new article: Fiberglassing.) |
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Cut foam to shape with a handsaw, putty knife, or bandsaw. Then, fit and glue pieces of foam larger than your layout on the board. A hot melt glue gun makes gluing this foam fast and easy. You can also glue the foam down with an expanding urethane glue, such as [http://www.gorillaglue.com/home.htm Gorilla glue], or some of the expanding foam that comes in an aerosol can. The different glues can make sanding over seam lines difficult, as they are usually a different density and hardness than the surrounding foam. | Cut foam to shape with a handsaw, putty knife, or bandsaw. Then, fit and glue pieces of foam larger than your layout on the board. A hot melt glue gun makes gluing this foam fast and easy. You can also glue the foam down with an expanding urethane glue, such as [http://www.gorillaglue.com/home.htm Gorilla glue], or some of the expanding foam that comes in an aerosol can. The different glues can make sanding over seam lines difficult, as they are usually a different density and hardness than the surrounding foam. | ||
| − | Shaping this foam also can be done with sandpaper, | + | Shaping this foam also can be done with sandpaper, surform files, knives, and picks. Even your fingers can shape this foam quite easily and rapidly. |
Keep the hot melt glue away from where you will be sanding. It is gummy and will not sand properly, making your buck a lot harder to shape than it needs to be. | Keep the hot melt glue away from where you will be sanding. It is gummy and will not sand properly, making your buck a lot harder to shape than it needs to be. | ||
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One step that I do on these kinds of parts is to paint the buck with resin after shaping it. It makes it a little more dimensionally stable, and toughens up the surface for the next steps. | One step that I do on these kinds of parts is to paint the buck with resin after shaping it. It makes it a little more dimensionally stable, and toughens up the surface for the next steps. | ||
| − | Once I have painted the buck with resin I can clay up any low spots with modeling clay, and then wax the resin. I then spray a coating of polyvinyl | + | Once I have painted the buck with resin I can clay up any low spots with modeling clay, and then wax the resin. I then spray a coating of polyvinyl alcohol on the waxed surface. Polyvinyl alcohol, or "PVA", is a water-soluble plastic commonly used as a release and sealing agent for molds. Using PVA will make removing the foam much easier after the part is laid up. |
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This article assumes that you have a basic knowledge of laminating with [[Fiberglassing|fiberglass]]. Follow all instructions provided with your materials in regard to proper catalyzation of the resin and storage and handling of your tools and materials. | This article assumes that you have a basic knowledge of laminating with [[Fiberglassing|fiberglass]]. Follow all instructions provided with your materials in regard to proper catalyzation of the resin and storage and handling of your tools and materials. | ||
| − | Cut strips of 1 1/2 oz fiberglass mat on a | + | Cut strips of 1 1/2 oz fiberglass mat on a piece of cardboard, ready to be wetted out. 3 layers of 1 1/2 oz mat will make a part that is about 0.120" thick, as each layer contributes about .040" to the laminate. There will be an extra layer laminated around all of the edges to make the final part about 0.160" thick. |
When wetting out mat with resin, many people work the resin into the mat while it is on the wet out board. This is a mistake and will only make a resin rich, inconsistent part. You only brush enough resin on to cover the mat with resin. Then, give it a little bit of time, and it will soak in. | When wetting out mat with resin, many people work the resin into the mat while it is on the wet out board. This is a mistake and will only make a resin rich, inconsistent part. You only brush enough resin on to cover the mat with resin. Then, give it a little bit of time, and it will soak in. | ||
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| − | Cut your material so that you have at least 1" of overlap onto the previously laid up section. Stagger the layers so you don't create a big lump. A trick that professional glass guys use is to tear the edges of the mat. This tapers the thickness down at the edge, making a smoother overlap. Done correctly and applied while the previous lay up is still workable, you won't be able to tell that the part was made from separate pieces of mat, instead of one | + | Cut your material so that you have at least 1" of overlap onto the previously laid up section. Stagger the layers so you don't create a big lump. A trick that professional glass guys use is to tear the edges of the mat. This tapers the thickness down at the edge, making a smoother overlap. Done correctly and applied while the previous lay up is still workable, you won't be able to tell that the part was made from separate pieces of mat, instead of one continuous piece. |
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After the part has been trimmed and the surface has been lightly ground, with any high spots ground down, and any air bubbles opened up, a skim coat of body filler can be applied. Any decent body filler that will stick to fiberglass will work. Scrub a light coat into the surface in 3 or 4 directions before applying the fill coat, this will get the filler into the pores better. The part is still left on the foam and plywood buck because it is easier to handle during the bodywork phase. | After the part has been trimmed and the surface has been lightly ground, with any high spots ground down, and any air bubbles opened up, a skim coat of body filler can be applied. Any decent body filler that will stick to fiberglass will work. Scrub a light coat into the surface in 3 or 4 directions before applying the fill coat, this will get the filler into the pores better. The part is still left on the foam and plywood buck because it is easier to handle during the bodywork phase. | ||
| − | As this is a one-off fan shroud, special fairing techniques are not employed in its execution. A DA sander with 80 grit is used in all | + | As this is a one-off fan shroud, special fairing techniques are not employed in its execution. A DA sander with 80 grit is used in all accessible areas, and hand sanding in the corners is done with 80 grit as well. |
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